1. Field of the Invention
This invention relates to an improved car plug used to derive power by utilizing a socket, which is a jack portion for a cigar lighter mounted in a cabin of an automobile, to derive power by inserting a plug used to derive power, instead of the cigar lighter, into the socket after removing the cigar lighter from the socket.
2. Description of the Prior Art
A socket 1 for a cigar lighter mounted in a cabin of an automobile is assembled as follows. That is, as shown in FIG. 1, a cylindrical body 10 serving as an outside electrode is made of a metal material, an axial rod-like inside electrode 11 is incorporated integrally with the bottom of the body through an insulating material 12, a hold piece 13 to hold an inserted cigar lighter is incorporated with the inner end side of the inside electrode 11, a cord holder 15 is incorporated by the use of a nut 16 with an outer end portion of the inside electrode 11 projected from the outer surface of the bottom of the body 10 through an insulating material 14, and an earthing conductor connected to the body 10 and a cord 17 connected to the inside electrode 11 are held by the cord holder. Then, the socket 1 thus assembled is incorporated in a vehicle body.
A car plug A inserted into the socket to derive power is assembled as follows. That is, as shown in FIG. 2, an inside electrode terminal 3 is incorporated with the top side of an axially cylindrical body 2 made of an insulating material, one of cords 40, 40 inserted into the body 2 from its tail end side is connected to the inside electrode terminal through a fuse 30, elastic terminals 5, 5 serving as outside electrodes are fitted in the body 2, terminal portions 50, 50 at the top side of the elastic terminals are projected from the outer surface of the body 2 through window holes 20, 20 provided in a peripheral wall of the body 2, and the tail ends of the elastic terminals are connected to the other cord 40. Thus, when the car plug A is inserted into the socket 1, the inside electrode terminal 3 at the top of the body of the car plug is brought into contact with and connected to the inside electrode 11 at the bottom of the body 10 of the socket 1, and the terminal portions 50, 50 projected from the outer surface of the body 2 are brought into contact with and connected to the inner surface of the cylindrical body 10 of the socket 1. As a result, the car plug is used to derive power through the cords 40, 40.
In the socket 1 for the cigar lighter mounted in a body of an automobile, the body 10 is standardized to have the same inside diameter in Japanese automobiles and U.S automobiles. However, a socket 1' in European automobiles such as Mercedes-Benz is formed to have a somewhat larger inside diameter (by an extent of about 1 mm) as shown in FIG. 3.
Thus, when the car plug A produced to be adapted for Japanese automobiles so as to derive power is inserted into the socket 1' in European automobiles to make an attempt to derive power, the terminal portions 50, 50 of the car plug A are brought into insufficient contact with the inner surface of the body 10 of the socket 1', and as a result, there are generated problems of a drop of the inserted car plug A out of the socket 1', or failure of electrical contact between the terminal portions 50, 50 and the body 10.
In view of the above problems, the car plug A has a following structure. That is, a support member a is provided in the body 2 of the car plug to support the elastic terminals 5 so as to project the terminal portions 50 through the window holes 20 of the body 2. Further, the support member a is axially supported by a rotary shaft b rotated by the operation performed outside the body 2, so that a position to support the elastic terminals is varied in the radial direction of the body 2 through rotation of the rotary shaft as shown in FIG. 4, and the height of each terminal portion 50 projected from the window hole 20 is switched over between higher and lower levels through switch-over of the support position to cope with a variation of the inside diameter of the body 10 in the socket 1.
When the conventional car plug A described above is inserted into the socket 1' of a large diameter in European automobiles, the elastic terminals 5 are supported so as to push a longitudinal intermediate portion of each elastic terminal in the radial direction by rotating the support member a to a position in a state as shown in FIG. 4 through the operation of an operating portion c, and as a result, the terminal portions 50 are projected to a higher position, as shown in FIG. 5. When the car plug A is inserted into the socket 1 of a small diameter in Japanese automobiles, the support member a is released from the elastic terminals 5 by rotating the support member a to a position in a state as shown in FIGS. 2 and 6 through the operation of the operating portion c, and as a result, the terminal portions 50 are projected to a lower position. Thus, the car plug A is adapted for both the socket 1 of the small diameter and the socket 1' of the large diameter. However, the switching operation is troublesome, and it is difficult to confirm the switched state since the support member a, which is provided in the body 2 and not observed from the outside, is rotated and switched over outside the body 2. Thus, there are generated problems in that the car plug is damaged or not pulled out from the socket in case where the car plug is set to be adapted for the socket 1' of the large diameter, and in this state, this car plug is forcibly inserted into the socket 1 of the small diameter.